Last time Apple did a battery case, it only worked with the 4.7-inch iPhone 7. The battery life claims for this one on the two larger iPhone models, in particular, are ridiculous. Juli Clover, MacRumors:
Each case provides a varying amount of battery life depending on device. The iPhone XS Battery Case, when paired with the iPhone XS, offers up to 33 hours of talk time, up to 21 hours of internet use, and up to 25 hours of video playback.
The iPhone XS Max with the XS Max Smart Battery Case offers up to 37 hours of talk time, up to 20 hours of internet use, and up to 25 hours of video playback.
The iPhone XR with the XR Battery Case offers up to 39 hours of talk time, up to 22 hours of internet use, and up to 27 hours of video playback.
If you travel a lot, this might just be the quickest purchase you make. Curiously, the iPhone X is not officially supported by the iPhone XS case; I wonder if it’s just a slight difference in the size of the camera cutout — which, I bet, would be trivial to work around — or if there’s some other compatibility roadblock.